TY - JOUR
T1 - Nucleoside diphosphate kinase A/NM23-H1 binds to the <em>c-myc</em> promoter and regulates its transcription
JF - Cancer Research
JO - Cancer Res
SP - 222
LP - 222
VL - 64
IS - 7 Supplement
AU - Chang, Christina L.
Y1 - 2014/10/23
UR - http://cancerres.aacrjournals.org/content/64/7_Supplement/222.3.abstract
N2 - Proc Amer Assoc Cancer Res, Volume 45, 2004 976 Nucleoside diphosphate kinase isoforms A (NDPK-A) and B (NDPK-B) share 88% identical amino acid residues and are encoded by the nm23-H1 and nm23-H2 genes, respectively. NDPK-B has been shown to regulate c-myc transcription via the nuclease hypersensitive element (NHE) III1, it is likely that NDPK-A has a similar function because of its homology and interaction with NDPK-B. In this study, we have demonstrated that NDPK-A formed a complex with c-myc NHE III1, spanning from –142 to –115 relative to the P1 start site, in the electrophoretic mobility shift assay (EMSA). NDPK-A interacted specifically with double-stranded (ds) as well as single-stranded (ss) c-myc based on DNA competition and protein depletion experiments. NDPK-A bound to the pyrimidine- and purine-rich strand with similar affinity. Compared to NDPK-B, however, NDPK-A displayed a significant lower binding affinity toward c-myc DNA based on EMSA and UV-crosslinking. Similar to many human cancer cell lines, NB69 neuroblastoma cells expressed detectable NDPK-B, but not NDPK-A, according to Western blot analysis. Deletion of the NHE III1 (i.e., –293 to –104) from the c-myc promoter, spanning from –1676 to +374, de-repressed the CAT activity by approximately 6 folds. Stable transfectants established from NB69 cells overexpressed NDPK-A and the latter was localized to nuclei by immunohistochemistry. These transfectants only de-repressed the CAT activity by 3 folds when the NHE III1 was deleted from the c-myc promoter. Additional de-repression appeared to require c-myc promoter region upstream of the NHE III1. Our findings suggest that NDPK-A participates in the regulation of c-myc transcription by directly interacts with NHE III1 in the promoter. Alternatively, NDPK-A may be indirectly involved in c-myc gene regulation by affecting the DNA-binding ability of NDPK-B via the protein-protein interaction. NDPK-B appeared to repress c-myc transcription in human neuroblastoma cell, perhaps via tissue-specific proteins that regulate c-myc promoter.
ER -